Furanoid stress metabolites have been implicated in outbreaks of respiratory disease in cattle fed mold-damaged sweet potatoes. The research outlined in the proposal is concerned with the metabolic activation of one of the lung toxic furans, 4-ipomeanol, in animals and the biosynthesis of furanosesquiterpenes in the plant. Research on the metabolic activation of 4-ipomeanol will involve isolation of the glutatione conjugate(s) resulting from microsomal incubations of the furan and glutathione. Modified amino acids from protease digestion of microsomal protein to which 4-ipomeanol has been covalently bound will also be isolated. The structure of the furan conjugates will be determined using proton FTNMR. Unidentified, Ehrlich-positive stress metabolites will be isolated from sweet potatoes by HPLC. Preliminary toxicity testing will be done on all new metabolites. More intensive testing will be done if preliminary results warrant. Biosynthetic studies will procede by first determining the product -precursor relationship of the furanosesquiterpenes using 14C-labeled compounds. Details of the biosynthesis will be investigated using 14C-labeling studies as well as 18O, 17O, or other isotopic labeling. Finally, the modification of the stress metabolites by fungi normally found on sweet potatoes will be examined. After the true stress metabolites of the plant have been identified, those present in mold-damaged sweet potatoes due to catabolism by the fungus will be investigated.